Apparatus and method for electrochemically processing a microelectronic workpiece

ABSTRACT

A reactor for use in electrochemical processing of a microelectronic workpiece is set forth and described herein. The apparatus comprises one or more walls defining a processing space therebetween for containing a processing fluid. The processing space includes at least a first fluid flow region and a second fluid flow region. A first electrode is disposed in the processing fluid of the first fluid flow region while a second electrode, comprising at least a portion of the microelectronic workpiece, is disposed in the processing fluid of the second fluid flow region. Fluid flow within the first fluid flow region is generally directed toward the first electrode and away from the second electrode while fluid flow within the second fluid flow region is generally directed toward the second electrode and away from the first electrode. Depending on the particular electrochemical process that is to be executed, the first e electrode may constitute either an anode or a cathode in the electrochemical processing of the microelectronic workpiece. The foregoing reactor architecture is particularly useful in connection with electroplating of the microelectronic workpiece and, more particularly, in electroplating operations that employ a consumable anode, such as a phosphorized copper anode.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

The present invention is directed to an apparatus for electrochemicallyprocessing a microelectronic workpiece. More particularly, the presentinvention is directed to a reactor assembly for electrochemicallydepositing, electrochemically removing and/or electrochemically alteringthe characteristics of a thin film material, such as a metal ordielectric, at the surface of a microelectronic workpiece, such as asemiconductor wafer. For purposes of the present application, amicroelectronic workpiece is defined to include a workpiece formed froma substrate upon which microelectronic circuits or components, datastorage elements or layers, and/or micro-mechanical elements are formed.

Production of semiconductor integrated circuits and othermicroelectronic devices from workpieces, such as semiconductor waters,typically requires formation and/or electrochemical processing of one ormore thin film layers on the wafer. These thin film layers are often inthe form of a deposited metal that is used, for example, to electricallyinterconnect the various devices of the integrated circuit. Further, thestructures formed from the metal layers may constitute microelectronicdevices such as read/write heads, etc.

The microelectronic manufacturing industry has applied a wide range ofthin film layer materials to form such microelectronic structures. Thesethin film materials include metals and metal alloys such as, forexample, nickel, tungsten, tantalum, solder, platinum, copper,copper-zinc, etc., as well as dielectric materials, such as metaloxides, semiconductor oxides, and perovskite materials.

A wide range of processing techniques have been used to deposit and/oralter the characteristics of such thin film layers. These techniquesinclude, for example, chemical vapor deposition (CVD), physical vapordeposition (PVD), anodizing, electroplating, and electroless plating. Ofthese techniques, electrochemical processing techniques (i.e.,electroplating, anodizing, and electroless plating) tend to be the mosteconomical and, as such, the most desirable. Such electrochemicalprocessing techniques can be used in the deposition and/or alteration ofblanket metal layers, blanket dielectric layers, patterned metal layers,and patterned dielectric layers.

One of the process sequences used in the microelectronic manufacturingindustry to deposit a metal onto semiconductor wafers is referred to as“damascene” processing. In such processing, holes, commonly called“vias”, trenches and/or other micro-recesses are formed onto a workpieceand filled with a metal, such as copper and/or a copper alloy. In thedamascene process, the wafer is first provided with a metallic seedlayer which is used to conduct electrical current during a subsequentmetal electroplating step. If a metal such as copper is used, the seedlayer is disposed over a barrier layer material, such as Ti, TiN, etc.The seed layer is a very thin layer of metal, such as copper, gold,nickel, palladium, etc., which can be applied using one or more ofseveral processes. The seed layer is formed over the surface of thesemiconductor wafer, which is convoluted by the presence of the vias,trenches, or other recessed device features.

A metal layer is then electroplated onto the seed layer in the form of ablanket layer. The blanket layer is plated to form an overlying layer,with the goal of providing a metal layer that fills the trenches andvias and extends a certain amount above these features. Such a blanketlayer will typically have a thickness on the order of 10,000 to 15,000angstroms (1-1.5 microns).

After the blanket layer has been electroplated onto the semiconductorwafer, excess metal material present outside of the vias, trenches, orother recesses is removed. The metal is removed to provide a resultingpattern of metal layer in the semiconductor integrated circuit beingformed. The excess plated material can be removed, for example, usingchemical mechanical planarization. Chemical mechanical planarization isa processing step which uses the combined action of a chemical removalagent and an abrasive which grinds and polishes the exposed metalsurface to remove undesired parts of the metal layer applied in theelectroplating step.

The electroplating of the semiconductor wafers takes place in a reactorassembly. In such an assembly, an anode electrode is disposed in aplating bath, and the wafer with the seed layer thereon is used as acathode. Only a lower face of the wafer contacts the surface of theplating bath. The wafer is held by a support system that also conductsthe requisite electroplating power (e.g., cathode current) to the wafer.

Several technical problems must be overcome in designing reactors usedin the electrochemical processing of microelectronic workpieces, such assemiconductor wafers. One such problem relates to the formation ofparticulates contamination, gas bubbles, etc., that form at the surfaceof the anode (or, in the case of anodization, both the cathode andanode) during the electrochemical process. Although such problems existin connection with the wide range of electrochemical processes, thediscussion below focuses on those problems associated withelectroplating a metal onto the surface of the microelectronicworkpiece.

Generally stated, electroplating occurs as a result of anelectrochemical reduction reaction that takes place at the cathode,where atoms of the material to be plated are deposited onto the cathodeby supplying electrons to attract positively charged ions. The atoms areformed from ions present in the plating bath. In order to sustain thereaction, the ions in the plating bath must be replenished.Replenishment is generally accomplished through the use of a consumableanode or through the use of an external chemical source, such as a bathadditive, containing the ions or an ion-forming compound.

As the thin film layer is deposited onto the cathode, a correspondingelectrochemical oxidation reaction takes place at the anode. During thiscorresponding electrochemical reaction, byproducts from theelectrochemical reaction, such as particulates, precipitates, gasbubbles, etc. may be formed at the surface of the anode. Such byproductsmay then be released into the processing bath and interfere with theproper formation of the thin-film layer at the surface of themicroelectronic workpiece. Furthermore if these byproducts are allowedto remain present in the processing fluid at elevated levels near theanode, they can affect current flow during the plating process and/oraffect further reactions that must take place at the anode if theelectroplating is to continue. For example, if copper concentrations areallowed to increase excessively, copper sulfate will precipitate due tothe common ion effect. In order to reduce and or eliminate this problem,electrolyte flow near the anode is maintained at a sufficient level toallow mixing of the dissolved species in the electrolyte.

Such byproducts can be particularly problematic in those instances inwhich the anode is consumable. For example, when copper is electroplatedonto a workpiece using a consumable phosphorized copper anode, a blackanode film is produced. The presence and consistency of the black filmis important to ensure uniform anode erosion. This oxide/salt film isfragile, however. As such, it is possible to dislodge particulates fromthis black film into the electroplating solution. These particulates canthen potentially be incorporated into the deposited film with theundesired consequences.

One technique for limiting the introduction of particulates and/orprecipitates produced at the anode into the plating bath, has been toenclose the anode in an anode bag. The anode bag is typically made of aporous material, which generally traps larger size particulates withinthe anode bag, while allowing smaller size particulates to be releasedexternal to the bag and into the plating bath. As the features of thestructures and devices formed on the microelectronic workpiece decreasein size, however, the performance of the structures and devices may bedegraded by even the smaller size particulates. Furthermore, while theuse of an anode bag will restrict the larger particulates from travelingtoward the cathode and contaminating the plating surface or affectingthe plating process taking place at the cathode, the anode bag will alsotrap the larger particulates within the proximity of the anode creatingelevated levels of these byproducts, which may limit the forwardelectrochemical reaction taking place at the anode. Still further, thelarger particulates can eventually block the porous nature of the anodebag and ultimately restrict even the regular fluid flow.

The present inventors have recognized the foregoing problems and havedeveloped a method and apparatus that assists in isolating byproductsthat form at an electrode of an electrochemical processing apparatus toprevent them from interfering with the uniform electrochemicalprocessing of the workpiece.

BRIEF SUMMARY OF THE INVENTION

A reactor for use in electrochemical processing of a microelectronicworkpiece is set forth and described herein. The apparatus comprises oneor more walls defining a processing space therebetween for containing aprocessing fluid. The processing space includes at least a first fluidflow region and a second fluid flow region. A first electrode isdisposed in the processing fluid of the first fluid flow region while asecond electrode, comprising at least a portion of the microelectronicworkpiece, is disposed in the processing fluid of the second fluid flowregion. Fluid flow within the first fluid flow region is generallydirected toward the first electrode and away from the second electrodewhile fluid flow within the second fluid flow region is generallydirected toward the second electrode and away from the first electrode.Depending on the particular electrochemical process that is to beexecuted, the first electrode may constitute either an anode or acathode in the electrochemical processing of the microelectronicworkpiece. The foregoing reactor architecture is particularly useful inconnection with electroplating of the microelectronic workpiece and,more particularly, in electroplating operations that employ a consumableanode, such as a phosphorized copper anode.

In accordance with one embodiment of the invention, the reactorcomprises at least one pressure drop member disposed in the processingfluid of the processing space in an intermediate position between thefirst and second fluid flow regions and the first and second fluid flowregions are adjacent one another.

The pressure drop member may comprise a permeable membrane that isdisposed over an open end of a cup assembly wherein the membrane ispermeable to at least one of the ionic species in the processing fluid.The cup assembly may comprise an electrode housing assembly having aninverted lip, and an outer cup assembly. In accordance with a furtherenhancement of this embodiment, the cup assembly further includes atleast one outlet tube having an opening, which extends into the spacewithin the inverted unshaped lip of the electrode housing assembly. Theoutlet tube provides a path for processing fluid, gas bubbles, andparticulates to exit the cup assembly, while the pressure drop memberrestricts movement of the same into the second fluid flow region of thecup assembly.

A method for processing a microelectronic workpiece is also set forth.In accordance with one embodiment of the method, a processing spacecontaining processing fluid is divided into at least a first fluid flowregion and a second fluid flow region. A first electrode is locatedwithin the processing fluid of the first fluid flow region and a secondelectrode comprising at least a portion of the microelectronic workpieceis located within the processing fluid of the second fluid flow region.A fluid flow of the processing fluid is generated within the first fluidflow region that is generally directed toward the first electrode andgenerally away from the second electrode while a fluid flow of theprocessing fluid within the second fluid flow region is generated thatis generally directed toward the second electrode and generally awayfrom the first electrode.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a cross sectional side view of a plating reactor inaccordance with the present invention.

FIG. 2 illustrates an isometric view of a conically shaped frame of apressure drop member for use in the plating reactor illustrated in FIG.1.

FIG. 3 illustrates an isometric view of the pressure drop memberincluding the conically shaped frame, illustrated in FIG. 2, and amembrane attached thereto.

FIG. 4 illustrates an enlarged cross-sectional view of a portion of theplating reactor illustrated in FIG. 1.

FIG. 5 illustrates an isometric view of one example of a field shapingelement for use in the plating reactor illustrated in FIG. 1.

FIG. 6 illustrates an isometric view of another example of a fieldshaping element for use in the plating reactor illustrated in FIG. 1.

FIG. 7 illustrates an enlarged cross-sectional view of a portion of theplating reactor illustrated in FIG. 1, with the field shaping elementsillustrated in FIGS. 5 and 6 similarly shown.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a cross-sectional side view of a reactor, showngenerally at 10, for electrochemical processing of a microelectronicworkpiece in accordance with one embodiment the present invention. Inthe particular embodiment of the invention shown here, the reactor isadapted for electrochemical deposition of a metal, such as copper orcopper alloy, on the surface of the microelectronic workpiece.Accordingly, the following description includes express references toelements used in such electrochemical deposition processes. It will berecognized, however, that the reactor architecture is suitable for awide range of electrochemical processing operations including, forexample, anodization of a surface of the workpiece.

The reactor 10 has a reactor head assembly 20 that assists in supportingthe workpiece during processing, and a corresponding processing space inthe form of a reactor bowl assembly 30. Reactor bowl assembly 30includes one or more walls that define a processing space that containsa processing fluid, as will be set forth in further detail below. Thistype of reactor assembly is particularly suited for effectingelectroplating of semiconductor waters or like workpieces, in which thewafer is electroplated with a blanket or patterned metallic layer.

The reactor head assembly 20 and the reactor bowl assembly 30 of theillustrated embodiment may be moved relative to one another. Forexample, a lift and rotate mechanism, not shown, may be used inconjunction with the head and bowl assemblies 20, 30 to drive thereactor head 20 in a vertical direction with respect to the reactor bowlassembly 30 and to rotate the reactor head assembly 20 about ahorizontally disposed axis. By lifting and rotating the reactor headassembly 20, a workpiece 45, such as a semiconductor wafer, may be movedbetween a load position that allows the workpiece 45 to be placed uponthe head assembly 20, and a processing position in which at least aportion of the workpiece 45 is brought into contact with processingfluid in the processing space of the reactor bowl assembly 30. When theworkpiece is in the processing position, it is generally oriented withthe process side down within the processing space. When the workpiece 45is in the load position, the workpiece 45 is generally exposed outsideof the reactor bowl assembly 30 with the process side directed upward,for loading and unloading by, for example, a robotic wafer transfermechanism. One example of a suitable lift and rotate mechanism isdescribed in connection with U.S. patent application Ser. No.09/351,980, filed Jul. 12, 1999, entitled “Lift and Rotate Mechanism forUse in a Workpiece Processing Apparatus”, the disclosure of which isincorporated herein by reference.

Preferably, the reactor head assembly 20 includes a stationary assembly50 and a rotor assembly 55. The rotor assembly 55 is configured with oneor more structures that serve to support the workpiece and to rotate theworkpiece 45 about a generally vertical axis during, for example,workpiece processing.

In the reactor embodiment of FIG. 1, the workpiece 45 is held in place,with respect to the rotor assembly 55 by contact assembly 60. Inaddition to holding the workpiece 45 in place, the contact assembly 60may include one or more electrical contacts that are disposed to engagethe workpiece 45 for applying electrical power used in theelectrochemical processing, operation. One embodiment of a contactassembly is described in detail in connection with U.S. patentapplication Ser. No. 09/386,803, filed Aug. 31, 1999 entitled “Methodand Apparatus for Processing the Surface of a MicroelectronicWorkpiece”, the disclosure of which is incorporated herein by reference.It will be recognized, however, that other contact architectures, suchas discrete finger contacts or the like, are also suitable depending onthe desired electrochemical processing that is to take place in thereactor 10. One J-hook design described in connection with U.S. patentapplication Ser. No. 08/680,057, filed Jul. 15, 1996, entitled“Electrode Semiconductor Workpiece Holder”, the disclosure of which issimilarly incorporated herein by reference.

During processing, the workpiece 45 is brought into contact withprocessing fluid located within, the reactor bowl assembly 30. In theillustrated embodiment, reactor bowl assembly 30 comprises a reactorbase assembly 65 that, in turn, includes process cup assembly 75 and anelectrode housing assembly 70. The process cup assembly 75 includes aplurality of wall structures that define a processing spacetherebetween. The electrode housing assembly 70 is located within theprocess cup assembly 75 and includes therein an electrode 105 used inelectrochemical processing of a workpiece 45.

Generally stated, the processing space within the process cup assembly75 includes at least two process fluid flow regions. The first fluidflow region is proximate the upper end and interior to the electrodehousing assembly 70 while the second flow region includes the region atthe upper end of processing cup 75 proximate workpiece 45. As will beexplained in further detail below, processing fluid flow in the firstfluid flow region is generally directed toward the interior of theelectrode housing assembly 70 and, more particularly, toward a surfaceof the electrode 105, and generally away from the workpiece 45. Incontrast, the flow of processing fluid in the second fluid flow regionis generally directed toward the workpiece 45 and generally away fromelectrode 105. One arrangement of structures that can be used toaccomplish this fluid flow pattern is described in detail below.

The electrode housing assembly 70 of the illustrated embodiment includesa housing member 72, which is generally bowl shaped and includes an endthat is open toward the workpiece 45. A pressure drop member 90 isdisposed over the open end of the housing member 72. The pressure dropmember 90 assists in dividing the processing space into theaforementioned first fluid flow region 95 and second fluid flow region100.

The housing member 72 may have a lip 80 located at the opening or therim thereof that extends radially inwards and then downward toward thebase of the assembly. The lip 80 may have a cross section in the shapeof an inverted “u” that defines a space 85 located therein, whichextends around the circumference of the electrode housing assembly 70.The lip 80 may serve as the locus of the engagement between the housingmember 72 and the pressure drop member 90. Together, the housing member72 and pressure drop member 90 define an interior electrode chamber inwhich electrode 105 is disposed.

The pressure drop member 90 may be conically shaped, and have an apexoriented so as to extend downward into the interior electrode chamber.To this end, the pressure drop member 90 may comprise a conically shapedframe 110, and a permeable membrane 115 that is fixed with the surfaceof the conically shaped frame 110. The conically shaped frame 110 isparticularly illustrated in FIG. 2 while the conically shaped frame 110with the membrane 115 fixed thereto is particularly illustrated in FIG.3. The membrane 115 may be fluid permeable or only permeable to at leastone of the ionic species in the processing fluid. In this latterinstance, the reactor may be augmented with separate inlets and outletsrespectively associated with each of the fluid flow regions.

FIG. 2 is an isometric view of the conically shaped frame 110 of thepressure drop member 90. The conically shaped frame 110 includes acontinuous circular base member 120, and a plurality of ribs 125 whichextend between the circular base member 120 and the point 130 of theconical shape. In the frame 110 at the place where the point 130 of theconical shape would be located, the conically shaped frame 110 includesa circular opening 135. The opening 135 in the frames avoids a largearea near the point 130 of the conical shape, which might otherwise trapfluid and/or substantially restrict fluid or current flow Located aroundthe circumference of the circular base member 120 of the conicallyshaped frame I 10 is a protrusion 140, which extends outward from thecircular base member 12( ) and is adapted for engaging a groove 145located in the inverted u-shaped lip 80 of the electrode housingassembly 70 (shown more clearly in FIG. 4).

FIG. 3 is an isometric view of the pressure drop member 90, includingthe conically shaped frame 110 illustrated in FIG. 2, with the membrane115 attached thereto. The membrane 115 may be comprised of a plasticfilter type media, or other media that at least partially restricts theflow of processing fluid flow therethrough. The membrane 115 alsoassists in preventing larger size particulates, precipitates, and/or gasbubbles from crossings the pressure drop member 90 and entering thesecond fluid flow region The membrane 115 is preferably formed into aconical shape, by cutting a triangular pie-shaped notch in the membranematerial. The resulting edges formed by the triangular shaped notch maythen be joined and held together with, for example, a single ultrasonicweld seam 150. The membrane 115 is then attached to the conical shapedframe 110 using a similar ultrasonic weld along the ribs 125 and thecontinuous perimeter of the circular base member 120.

The circular base member 120, ribs 125 and membrane 115 are preferablyformed from polypropylene, polyethylene, polyvinylidene fluoride, orother fluorocarbon type plastic. Such plastics are generally chemicallyinert with respect to the processing which is likely to take place inthe plating reactor 10.

In an alternative embodiment, the pressure drop membrane is formed froma sufficiently resilient membrane which does not require an underlyingframe structure.

Further alternative embodiments include the pressure drop member beingformed from a pressed disk of porous ceramic or porous glass.

Referring back to FIG. 1, the plating reactor 10 further includes afluid inlet 155 located within a riser tube 160 near the bottom of thecup assembly 65 for receiving processing fluid. The processing fluid isgenerally received from a fluid reservoir located external to theplating reactor 10.

The processing fluid received via the fluid inlet 155 initially entersthe second fluid flow region 100 of the cup assembly 65 via the space165 formed between the electrode housing assembly 70 and the process cupassembly 75. The processing fluid generally follows a flow correspondingto the direction of arrows illustrated in FIG. 1. While in the secondfluid flow region 100, the processing fluid comes into contact with theworkpiece 45 when in a processing position.

By placing the anode 105 in the first fluid flow region 95 within theelectrode housing assembly 70 and having the processing fluid enter thecup assembly 65 via the second fluid flow region 100, the anode 105 isisolated from the fluid flow when the processing fluid initially entersthe cup assembly 65. Correspondingly, the processing fluid does notdirectly impinge upon the anode 105, which may be a consumable anode. Asa result the useful life of the anode 105 is prolonged.

In connection with the electrode housing assembly 70, the platingreactor includes a fluid outlet tube 165. The fluid outlet tube 165 hasan opening 170, which extends into the space 85 formed within theinverted unshaped lip 80 of the electrode housing assembly 70. Theaddition of processing fluid into second fluid flow region 100 via thefluid inlet 155 and the exit of fluid from the first fluid flow region95 via the opening 170 in the fluid outlet tube 165, creates a pressuredifferential between the first fluid flow region 95 and the second fluidflow region 100 in which the pressure in the first fluid flow region 95is lower than the pressure in the second fluid flow region 100. In theupper region of the reactor, fluid will flow from the second fluid flowregion 100 into the first fluid flow region 95 through the pressure dropmember 90 in an attempt to equalize pressure between the regions.

The pressure drop member 90 provides some resistance to the flow offluid across the semi-porous membrane 115. As such, the pressureequalizing flow of processing fluid is somewhat restricted. Restrictingthe flow of fluid across the pressure drop member 90 has severaleffects. For example, the flow of process fluid across the pressure dropmember 90 is distributed more evenly along the surface of the pressuredrop member 90. Further, the restricted flow facilitates generation of apressure differential between the first fluid flow region 95 and thesecond fluid flow region 100. Because the pressure in the second fluidflow region 100 is maintained at a level that is slightly higher thanthe pressure in the first region, fluid flow from the first fluid flowregion 95 into the second fluid flow region 100 across the pressure dropmember 90 is unlikely. This pressure differential, in turn, effectivelyrestricts passage of any byproducts formed at electrode 105 during theelectrochemical reaction to an area within the first fluid flow region95 and assists in preventing such byproducts from reaching the surfaceof the workpiece 45. Rather, the byproducts generated within fluid flowregion 95 can be directed from the processing space through the fluidoutlet tube 165. Such an arrangement allows for separate processing ofthe processing fluid overflowing weir 180 and fluid exiting fluid outlet165. Special filtering or processing of the processing fluid exiting thefirst fluid flow may be employed to particularly remove any of theunwanted byproducts before the processing fluid is mixed and/orprocessed with the processing fluid overflowing weir 180 forrecirculation to the plating reactor 10 via the fluid inlet 155. As aresult, exposure of the workpiece 45 to potentially harmful byproductsproduced at the electrode 105 is substantially limited and/or can moreeasily be controlled using the illustrated reactor architecture.

Since the pressure drop member 90 is conically shaped and extendsdownward into the electrode housing assembly 70, it has a surface at theinterior electrode chamber that is oriented at an angle. The angle atwhich the surface of the pressure drop member is defined so that thehighest point of the pressure drop member 90 is proximate to theu-shaped lip 80 of the electrode housing assembly 70. The angled surfaceof the pressure drop member directs any particulates, precipitates orgas bubbles formed at the electrode 105 away from the center of theelectrode housing assembly toward the periphery and into the space 85within the u-shaped lip 80 of the electrode housing assembly 70. Notonly does the angled surface of the pressure drop member move thebyproducts away from the center of the processing area where they canotherwise adversely affect uniform current flow, the pressure dropmember also assists in driving the byproducts toward the opening 170 ofthe fluid outlet tube 165. Eventually the particulates, precipitatesand/or gas bubbles exit the cup assembly 65 along with the processingfluid via fluid outlet tube 165. This is more clearly shown inconnection with FIG. 4

FIG. 4 illustrates an enlarged cross-sectional view of an upper portionof the electrode housing assembly 70 of FIG. 1. More particularly, itillustrates the portion of the reactor bowl assembly 30 at which thepressure drop member 90 engages the u-shaped lip 80 of the electrodehousing assembly 70, and also illustrates the fluid outlet tube 165 andthe opening 170 that facilitates fluid communication with the space 85defined by the u-shaped lip 80. One example of the potential directionof fluid flow exiting the first region 95 via the fluid outlet tube 165is illustrated by arrow 175.

Specifically, the fluid pressure at the opening 170 and inside the fluidoutlet tube 165 is lower than the fluid pressure located elsewhere inthe cup assembly 65. This is due in part to the opening 170 of the fluidoutlet tube 165 being below the overall level of the processing fluid.As a result of the lower pressure proximate the opening 170 of the fluidoutlet tube 165, fluid will migrate towards the opening 165 fromelsewhere in the cup assembly. More specifically, the fluid from thefirst region will generally migrate towards the space 85 within theU-shaped lip 80, which extends circumferentially around the outerperimeter of the cup assembly 65, proximate the opening 170. The fluidthen enters the tube 165 via the opening 170 and exits the reactor bowlassembly 30.

Although the fluid flow from the first fluid flow region 95 to thesecond fluid flow region 100 is restricted, charged particles requiredfor electrochemical processing of the workpiece 45 can still flow fromthe first fluid flow region 95 to the second fluid flow region 100across the pressure drop member 90, as charged particles will flowindependent of the fluid flow. This is possible if the particles aresuitably charged and are sized appropriately to make it through thepressure drop barrier.

In addition to fluid outlet tube 165, the processing fluid can furtherexit the cup assembly 65 via an overflow weir 180 located at the lip ofthe wall of the process cup assembly 75. The processing fluid, which hasoverflowed the overflow weir 180, can then be drained via a cup drainvalve 185 located near the bottom of the reactor bowl assembly 30.

In the embodiment illustrated in FIG. 1, the reactor bowl assembly 30further provides for one or more mounting, connections adapted forreceiving one or more field shaping elements at the internal surfacethereof near the lip of the wall of the process cup assembly 75. Morespecifically, in the preferred embodiment the mounting connectionsinclude one or more generally horizontal grooves 190 extending aroundthe circumference of the wall at different elevations.

Field shaping elements provide for fluid and/or current shaping ortailoring. The field shaping elements mounted in one of the lowergenerally horizontal grooves 190 further from the workpiece 45 providesfor more global shaping or tailoring of the flow of processing fluid andcurrent, while field shaping elements mounted in one of the higherhorizontal grooves 190 closer to the workpiece 45 provide for fluid andcurrent shaping in connection with a more specific point on theworkpiece 45.

In accordance with one embodiment used in the electroplating of copperonto the surface of the workpiece, a consumable phosphorized copperanode and two field shaping elements are used. The field shapingelements include a lower field shaping element 195 or diffuser plate(illustrated in FIG. 5) and an upper field shaping element 200 or shield(illustrated in FIG. 6).

FIGS. 5 and 6 are isometric views of two embodiments of field shapingelements 195, 200 that may be used in the reactor 10. The field shapingelements 195, 200 generally each comprise a single plate of materialhaving one or more openings through which plating fluid and/or currentis enabled to flow. Depending on the opening pattern a more controlleddistribution of plating fluid and current across the surface of theworkpiece 45 can be achieved. Although each of these elements isillustrated to include peripherally disposed notches, such notches areoptional but may be used to assist in securing the respective elementsin place within the reactor assembly in cooperation with othercorresponding structures.

FIG. 5 illustrates a first of the two preferred field shaping elements195 that may be concurrently used in the reactor bowl assembly 30. Thefirst field shaping element 195 includes a plurality of openings 205arranged approximately in a grid like pattern. However, a spiral patternmay also be used. In at least one of the preferred embodiments, thefirst field shaping element 195 is positioned in one of the lowerhorizontal grooves 190.

FIG. 6 illustrates a second of the two preferred field shaping elements200 that may be used along with the first field shaping element 195illustrated in FIG. 5. The second field shaping element 200 preferablyincludes a single larger opening 210 approximately centered in the fieldshaping element 200. The second field shaping element 200 directs theprocessing fluid and electrical current away from the edge of theworkpiece 45. In at least one embodiment, the second field shapingelement 200 may be positioned proximate to the workpiece 45 in one ofthe higher horizontal grooves 190.

Examples of field shaping elements or diffuser plates, includingdiffuser plates having alternative opening patterns, are furtherdescribed in connection with U.S. patent application Ser. No.09/351,864, filed Jul. 12, 1999, entitled “Diffuser with Spiral OpeningPattern for Electroplating Reactor Vessel”, the disclosure of which isincorporated herein by reference.

FIG. 7 illustrates an enlarged cross-sectional view of a portion of theplating reactor illustrated in FIG. 1, further illustrating oneparticular embodiment where the field shaping elements 195 and 200,illustrated in FIGS. 5 and 6, are each present in one of the pluralityof horizontal grooves 190 for receiving a field shaping element.Specifically, FIG. 7 illustrates the field shaping element 200 or shield(illustrated in FIG. 6) in one of the higher horizontal grooves, and thefield shaping element 195 or diffuser plate (illustrated in FIG. 5) inone of the lower horizontal grooves.

Use of the present invention in an electroplating process is not onlyenvisioned with respect the plating of copper onto a workpiece using aconsumable phosphorized anode, but is further envisioned as havingutility in any electroplating process where there is a desire to limitexposure of the cathode/workpiece to the products produced at the anode.For example, the above noted electroplating process is furtherenvisioned as having utility in connection with a process for platingnickel onto a workpiece using a consumable nickel sulfur anode, and aprocess for plating solder onto a workpiece using a consumable tin leadanode, or for anodic processing of a workpiece, in which gas is producedat the cathode.

Numerous modifications may be made to the foregoing system withoutdeparting from the basic teachings thereof. Although the presentinvention has been described in substantial detail with reference to oneor more specific embodiments, those of skill in the art will recognizethat changes may be made thereto without departing from the scope andspirit of the invention as set forth in the appended claims.

1-52. (canceled)
 53. A reactor for electrochemically processing amicroelectronic workpiece comprising: a fluid vessel; an ion selectivemembrane positioned in the vessel between a first fluid flow region anda second fluid flow region; a first fluid flow entry positioned toprovide a first processing fluid to the first fluid flow region; a firstfluid flow exit positioned to remove the first processing fluid from thefirst fluid flow region; a first electrode in fluid communication withthe first fluid flow region; a second fluid flow entry positioned toprovide a second processing fluid different than the first processingfluid to the second fluid flow region; a second fluid flow exitpositioned to remove the second processing fluid from the second fluidflow region; and a second electrode positioned to contact themicroelectronic workpiece while the second electrode and themicroelectronic workpiece are in fluid communication with the secondfluid flow region.
 54. The reactor of claim 53 wherein the membrane isselectively permeable to an ionic species in at least one of the firstand second processing fluids.
 55. The reactor of claim 53 wherein thefirst electrode is an anodic electrode and wherein the second electrodeis a cathodic electrode.
 56. The reactor of claim 53, further comprisingthe first and second processing fluids.
 57. The reactor of claim 56wherein the first and second processing fluids provide chemical speciesfor applying a metallic material to the microelectronic workpiece. 58.The reactor of claim 56 wherein the membrane is selectively permeable toan ionic species in at least one of the first and second processingfluids.
 59. The reactor of claim 53, further comprising a fluidreservoir coupled to the second fluid entry.
 60. The reactor of claim 53wherein the membrane has an at least partially conical shape.
 61. Thereactor of claim 53 wherein the membrane inclines upwardly in a radiallyoutward direction.
 62. The reactor of claim 53, further comprising aperforated element positioned between the second electrode and themembrane.
 63. The reactor of claim 53 wherein the first electrodeincludes an anode positioned in the vessel.